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How to handle a fainting episode: an immediate veterinary visit is a must to uncover the underlying cause of the loss of consciousness.

One minute your dog seems fine; the next he's passed out on the floor. What should you do? Fainting, or clinically speaking, syncope, is the temporary loss of consciousness followed by a spontaneous rapid recovery.

"Rather than an illness in itself, fainting is a symptom of illness caused by a lack of sufficient flow of oxygenated blood to the brain," says cardiologist Bruce Kornreich, DVM, Ph.D., ACVIM, at Cornell University College of Veterinary Medicine. His advice during an episode: "Carefully monitor your dog, never put your hand in his mouth, and contact a veterinarian immediately."

Syncope (SING-kuh-pee) can have many causes, Dr. Kornreich says, most commonly:

* Cardiac arrhythmia, or irregular heartbeat.

* Neurologic problems such as epileptic seizures.

* A drop in blood pressure due to certain heart medications, such as beta blockers, ACE inhibitors and calcium channel blockers, which are also used to treat a variety of other conditions.

* Low blood sugar (hypoglycemia), sometimes seen in puppies who lack adequate nutrition and fat reserves.

* Liver disease and system-wide infections.

* A malfunction of the parasympathetic nervous system (a branch of the autonomic nervous system), causing a drop in blood pressure, heart rate and blood flow to the brain. Excitement, stress and pain can be triggers.

* Cardiomyopathy-related heart dysfunction, resulting in insufficient pressure to pump blood to the brain.

Fainting can occur in dogs of any age, but those with cardiac or central nervous system diseases, both more common in older pets, are more vulnerable, Dr. Kornreich says. "Certain breeds are also more likely to experience syncope." They include Dachshunds, West Highland White Terriers, Boxers and German Shepherd Dogs.

If your dog has any fainting spell, note the date, its length of time, any other symptoms and precipitating event. If possible, take a video of the episode.

Because the underlying condition may be chronic, progressive or even life threatening, diagnosis is essential. "Your dog's veterinarian will review your dog's health history and perform a thorough physical examination," Dr. Kornreich says. "This should include baseline blood work to check electrolytes and glucose levels."

Low-blood glucose levels can verify hypoglycemia as a potential cause. If brain disease is suspected, the veterinarian might recommend a CAT scan or MRI imaging. A sample of cerebrospinal fluid, which bathes the brain and spinal cord, may also be obtained to rule out inflammation and/or infection in the central nervous system. In addition, to check for heart electrical function, a 24-hour electrocardiogram, obtained via a device called a Holter monitor a dog wears at home, may be recommended.

"Inappropriately fast heart rates can be treated with drugs, while inappropriately slow heart rates can be treated with pacemakers," Dr. Kornreich says. "Central nervous system disease and idiopathic [unknown origin] epilepsy can often be controlled with one or several anti-seizure medications. If a tumor is detected, surgery to remove it may help. If the side effects of medication are responsible for the fainting episodes, the veterinarian may halt these and prescribe alternatives. The prognosis for dogs with fainting episodes varies, depending upon the cause."

After an episode, restrict your dog's activity and keep him quiet until you and his veterinarian determine the cause, Dr. Kornreich says. "We had one canine patient with arrhythmias who collapsed while wading. The life-threatening issue was how to get that 70-pound Labrador out of the water immediately." The lesson here: "If there's any history of fainting, do not let your dog go swimming."

Dr. Kornreich describes a popular YouTube video featuring a Schnauzer fainting in response to greeting his owner, a soldier returning after a long deployment. "Viewers commented on how cute that was, but from a veterinary medical standpoint, it's not cute. There was something wrong, and the dog should have been evaluated immediately."

CORNELL STUDIES UNDERWAY

Cornell researchers are investigating the causes of arrhythmias that can cause fainting and the best treatments for them, Dr. Kornreich says. "Cardiology resident Dr. Eva Oxford is looking into the mechanism of arrhythmogenic right ventricular cardiomyopathy, a common disease in Boxers. Other cardiac rhythm-associated research interests at Cornel l have included inherited ventricular arrhythmias in German Shepherds and the mechanism of sick sinus syndrome- a condition in which a dog's natural pacemaker in the heart (the sinus node) fails to discharge, resulting in inappropriately slow heart rates in affected dogs."
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Title Annotation:MEDICINE
Publication:Dog Watch
Date:Apr 1, 2015
Words:713
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